Browsing by Author "Ponpandian N"

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ECOLOGICAL RISK ASSESSMENT OF SILICON DIOXIDE NANOPARTICLES IN A FRESH-WATER FISH LABEO ROHITA: HEMATOLOGY, IONOREGULATION AND GILL NA+/K+ATPASE ACTIVITY
(Ecotoxicology and Environmental Safety, 2015-05-19) Krishnapriya K; Ramesh M; Saravanan M; Ponpandian N
The fate and effect of nanomaterials in the environment has raised concern about their environmental risk to aquatic organisms. Silica nanoparticles (SiO2-NPs) find its uses in various fields and are inevitably released into the environment. However, the ecotoxicological effects of SiO2-NPs on the freshwater fish remain poorly understood. The aim of this study was to evaluate the effect of different concentrations (1, 5 and25mgL_1) of SiO2-NPs on certain hematological, ionoregulatory and enzymological profiles of a freshwater teleost fish Labeo rohita. Hematological parameters such as hemoglobin(Hb), hematocrit (Hct), red blood cells (RBC), white blood cells (WBC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) values were altered in SiO2-NPs treated groups. Likewise, plasma electrolytes such as plasma sodium (Na+), potassium (K+) and chloride (Cl-) levels and Na+/K+ATPase activity in gill of SiO2-NPs treated groups were altered in all concentrations throughout the study period (96h). The alterations of these parameters were found to be dependent on dose and exposure period. The results of the present study indicate that the alterations of these parameters may relate to physiological stress system to SiO2-NPs toxicity and also demonstrate that manufactured metaloxide NPs in aquatic environment may affect the health condition of the aquatic organisms
ELECTRODEPOSITION OF WO3 NANOSTRUCTURED THIN FILMS FOR ELECTROCHROMIC AND H2S GAS SENSOR APPLICATIONS
(Elsevier/ Journal of Alloys and Compounds 719, 71-81, 2017-09-30) Poongodi S; Palaniswamy Suresh Kumar; Mangalaraj D; Ponpandian N; Meena P; Yoshitake Masuda; Chongmu Lee
In this work, Vertically oriented WO3 nanoflakes array films was synthesized via the template free facile electrodeposition method at room temperature. WO3 nanoflakes arrays was adopted as an effective cathode electrode material in the electrochemical devices structure. The WO3 material exhibits superior electrochromic performance shows a larger optical modulation (68.89% at 550 nm), faster response time (tb = 1.93 s, tc = 2.87 s), a higher coloration efficiency of about 154.93 cm2 C−1 and with excellent cyclic stability over 2000 cycles without any degradation. Futhermore, WO3 nanoflakes array film was used for the detection of H2S gas that showed excellent response. A considerable increase in porosity and high surface roughness could be conducive for such an excellent and superior electrochromic characteristic as well as gas sensing performances. These results indicates that fabricated WO3 nanoflakes array film by a simple strategy holds a great promise for potential multifunctional applications such as smart windows, gas sensors and optical sensors.
ENHANCED PHOTOCATALYTIC ACTIVITY OF COBALT-DOPED CEO2 NANORODS
(Springer US/ Journal of sol-gel science and technology, 64 (3), 515-523, 2012-12-01) Sabari Arul N; Mangalaraj D; Pao Chi Chen; Ponpandian N; Meena P; Yoshitake Masuda
In this paper, CeO2 and cobalt-doped CeO2 nanorods synthesized by surfactant free co-precipitation method. The microstructures of the synthesized products were characterized by XRD, FESEM and TEM. The structural properties of the grown nanorods have been investigated using electron diffraction and X-ray diffraction. High resolution transmission electron microscopy studies show the polycrystalline nature of the Co-doped cerium oxide nanorods with a length of about 300 nm and a diameter of about 10 nm were produced. The X-ray Photoelectron spectrum confirms the presence of cobalt in cerium oxide nanorods. From BET, the specific surface area of the CeO2 (Co-doped) nanostructures (131 m2 g−1) is found to be significantly higher than that of pure CeO2 (52 m2 g−1). The Co-doped cerium nanorods exhibit an excellent photocatalytic performance in rapidly degrading azodyes acid orange 7 (AO7) in aqueous solution under UV illumination.
IMPROVED MICROBIAL GROWTH INHIBITION ACTIVITY OF BIO-SURFACTANT INDUCED AG–TIO2 CORE SHELL NANOPARTICLES
(Elsevier/ Applied Surface Science 327, 504-516, 2015-02-01) Nithyadevi D; Suresh Kumar P; Mangalaraj D; Ponpandian N; Viswanathan C; Meena P
Surfactant induced silver–titanium dioxide core shell nanoparticles within the size range of 10–50 nm were applied in the antibacterial agent to inhibit the growth of bacterial cells. The single crystalline silver was located in the core part of the composite powder and the titanium dioxide components were uniformly distributed in the shell part. HRTEM and XRD results indicated that silver was completely covered by titanium dioxide and its crystal structure was not affected after being coated by titanium dioxide. The effect of silver–titanium dioxide nanoparticles in the inhibition of bacterial cell growth was studied by means of disk diffusion method. The inhibition zone results reveal that sodium alginate induced silver–titanium dioxide nanoparticles exhibit 100% more antibacterial activity than that with cetyltrimethylbromide or without surfactant. UV–vis spectroscopic analysis showed a large concentration of silver was rapidly released into phosphate buffer solution (PBS) within a period of 1 day, with a much smaller concentration being released after this 1-day period. It was concluded that sodium alginate induced silver–titanium dioxide core shell nanoparticles could enhance long term cell growth inhibition in comparison with cetyltrimethylbromide or without surfactant. The surfactant mediated core shell nanoparticles have comparatively rapid, less expensive and wider applications in modern antibacterial therapy.
POROUS REDUCED GRAPHENE OXIDE (RGO)/WO3 NANOCOMPOSITES FOR THE ENHANCED DETECTION OF NH3 AT ROOM TEMPERATURE
(Royal Society of Chemistry, 2019) Jeevitha G; Abhinayaa R; Mangalaraj D; Ponpandian N; Meena P; Veena, Mounasamy; Sridharan, Madanagurusamy
Incorporation of reduced graphene oxide (rGO) modifies the properties of semiconducting metal oxide nanoparticles and makes it possible to tune the surface area and pore size to optimum values, which in turn improves their gas sensing properties. In this work, to improve the ammonia (NH3) gas sensing characteristics, reduced graphene oxide (rGO) was incorporated into tungsten oxide (WO3) nanospheres using a simple ultrasonication method. The rGO–WO3 nanocomposites exhibited porous nanosheets with nanospherical WO3 as observed with field-emission scanning electron microscopy (FE-SEM). The oxidation state of the rGO–WO3 nanocomposite was determined using X-ray photoelectron spectroscopy (XPS). Three ratios of (1, 5 and 10% rGO/WO3) nanocomposites and pure WO3 showed good selectivity towards NH3 at 10–100 ppm, and more remarkably at room temperature in the range of about 32–35 °C and at a relative humidity (RH) of 55%. The limit of detection (LOD) of the synthesized rGO–WO3 nanocomposites was 1.14 ppm, which will highly favour low detection ranges of NH3. The sensor response was 1.5 times higher than that of the bare WO3 nanospheres. The sensors showed excellent selectivity, ultrafast response/recovery times (18/24 s), reproducibility and stability even after one month of their preparation. We believe that metal oxides using the rGO modifier can improve the sensitivity and reduce the LOD towards NH3 and can be used effectively in real-time environmental monitoring.
POROUS REDUCED GRAPHENE OXIDE (RGO)/WO3 NANOCOMPOSITES FOR THE ENHANCED DETECTION OF NH3 AT ROOM TEMPERATURE
(Royal Society of Chemistry, 2019) Jeevitha G; Abhinayaa R; Ponpandian N; Meena P; Veena Mounasamy; Sridharan Madanagurusamy
Incorporation of reduced graphene oxide (rGO) modifies the properties of semiconducting metal oxide nanoparticles and makes it possible to tune the surface area and pore size to optimum values, which in turn improves their gas sensing properties. In this work, to improve the ammonia (NH3) gas sensing characteristics, reduced graphene oxide (rGO) was incorporated into tungsten oxide (WO3) nanospheres using a simple ultrasonication method. The rGO–WO3 nanocomposites exhibited porous nanosheets with nanospherical WO3 as observed with field-emission scanning electron microscopy (FE-SEM). The oxidation state of the rGO–WO3 nanocomposite was determined using X-ray photoelectron spectroscopy (XPS). Three ratios of (1, 5 and 10% rGO/WO3) nanocomposites and pure WO3 showed good selectivity towards NH3 at 10–100 ppm, and more remarkably at room temperature in the range of about 32–35 °C and at a relative humidity (RH) of 55%. The limit of detection (LOD) of the synthesized rGO–WO3 nanocomposites was 1.14 ppm, which will highly favour low detection ranges of NH3. The sensor response was 1.5 times higher than that of the bare WO3 nanospheres. The sensors showed excellent selectivity, ultrafast response/recovery times (18/24 s), reproducibility and stability even after one month of their preparation. We believe that metal oxides using the rGO modifier can improve the sensitivity and reduce the LOD towards NH3 and can be used effectively in real-time environmental monitoring.
SYNTHESIS OF CEO2 NANORODS WITH IMPROVED PHOTOCATALYTIC ACTIVITY: COMPARISON BETWEEN PRECIPITATION AND HYDROTHERMAL PROCESS
(Springer US/Journal of Materials Science:Materials in Electronics,24 (5),1644-1650, 2013-05-01) Sabari Arul N; Mangalaraj D; Tae Whan Kim; Pao Chi Chen; Ponpandian N; Meena P; Yoshitake Masuda
The main purpose of this article is to examine the surface free cerium oxide (CeO2) nanostructures prepared by different methods. CeO2 nanoparticles and nanorods were prepared by two different methods including precipitation and hydrothermal process. In precipitation process the nanoparticles were prepared at room temperature, while in hydrothermal process nanorods were prepared at high temperature. X-ray and electron diffraction analysis show the presence of CeO2. X-ray photoelectron spectroscopy (XPS) confirms the presence of CeO2 in both nanostructures. From BET, the specific surface area of nanorods (110 m2g−1) is found to be higher than nanoparticles (52 m2g−1). Also, the effect of morphology on their photodegradation of azo dye acid orange 7 (AO7) under UV–Visible light has been successfully investigated. The results show that the CeO2 nanorods synthesized by hydrothermal method have high surface area and exhibit improved performance in the photocatalytic activity.
TOXIC INFLUENCE OF PRISTINE AND SURFACTANT MODIFIED HALLOYSITE NANOTUBES ON PHYTOPATHOGENIC BACTERIA
(Elsevier/Applied Clay Science, 2019-06-15) Abhinaya R; Jeevitha G; Mangalaraj D; Ponpandian N; Meena P
Halloysite nanotube (Hal nanotube) – a clay mineral nanomaterial, was surface modified using cationic, anionic and non-ionic surfactants – cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulphate (SDS) and Tween 80 respectively. The pristine Hal nanotube and the three surfactant modified Hal nanotubes (SM-Hal nanotubes) were tested against three phytopathogenic bacteria Xanthomonasoryzae, Agrobacterium tumifeciens and Ralstoniasolanacearum. In the present study, by performing various bacterial toxicity assays, it has been established that SM-Hal nanotubes had a higher killing efficiency of phytopathogenic bacteria than pristine Hal nanotube. The surfactant modifications improved the dispersion of the Hal nanotube and altered the physico-chemical properties like grain size, particle diameter, surface charge and hydrophilicity, which consecutively enhanced the interaction and the toxic effects on phytopathogenic bacteria. SM-Hal nanotubes inhibited phytopathogenic bacteria at a lower minimum inhibitory concentration (MIC) as compared to the pristine Hal nanotube. Among the three SM-Hal nanotubes, CTAB-modified Hal nanotube effectively suppressed the growth, disrupted the cell membrane integrity, induced higher reactive oxygen species (ROS) production and inhibited the biofilm formation of all the three phytopathogenic bacteria followed by Tween 80-modified and SDS-modified Hal nanotubes. Hence, it is evident that these tailor made SM-Hal nanotubes, can be effectively used as potent clay mineral nanomaterials to control phytopathogenic bacteria.